When someone new breaks his way into a new group of friends due to change of circumstance. This can often cause confusion in the group with a change in the ranking of the alpha males or smaller characters in the group becoming left out and replaced.

Ben: I think Fister is coming over saturday night as well.
Karl: Fister?
Ben: you know Alex.
Karl: That bloody ringbreaker! who does he think he is! breaking into the gang and acting as if nothing has happened!!
Ben: Shut up karl.